Obesity is a major health concern in Western societies. It is estimated that about 97 million adults in the United States are overweight or obese. Obesity is now recognized as a chronic disease that requires treatment to reduce its associated health risks. The medical problems associated with obesity, which can be serious and life-threatening, include hypertension; type 2 diabetes mellitus; elevated plasma insulin concentrations; insulin resistance; hyperinsulinemia; glucose intolerance; dyslipidemias; hyperlipidemia; endometrial, breast, prostate and colon cancer; osteoarthritis; respiratory complications, such as obstructive sleep apnea; cholescystitis; cholelithiasis; gout; gallstones; gall bladder disease; respiratory problems; psychological disorders (such as depression, eating disorders, distorted body image and low self esteem); arteriosclerosis; heart disease; abnormal heart rhythms; angina pectoris; and heart arrythmias (Kopelman, P. G., Nature 404, 635-643 (2000)). Obesity is further associated with premature death and with a significant increase in mortality and morbidity from stroke, myocardial infarction, congestive heart failure, coronary heart disease, and sudden death. Recent studies have found that obesity and its associated health risks also affect children and adolescents. According to the Centers for Disease Control, 15 percent of children and adolescents are defined as overweight and obese, a doubling since the early 1970s. Important outcomes for the treatment of obesity include weight loss, and weight management to improve cardiovascular and metabolic health and to reduce obesity-related morbidity and mortality. It has been shown that 5-10% loss of body weight can substantially improve metabolic values, such as blood glucose, blood pressure, and lipid concentrations, and may reduce morbidity and mortality.
Cholecystokinin (CCK) is a brain-gut peptide that acts as a gastrointestinal hormone, neurotransmitter and neuromodulator in the central and the peripheral nervous systems. It has been shown that CCK is released from mucosal 1-cells of the duodenum and jejunum in response to a meal, particularly in response to fat or protein in the meal. Once released, CCK initiates a number of responses coordinated to promote digestion and regulate food intake, including mediating bile emptying from the gall bladder, regulating the release of digestive enzymes from the pancreas, controlling gastric emptying by regulation of the pyloric sphincter, as well as neuronal signaling to the central nervous system via vagal afferent neurons. Neuronal CCK is believed to mediate a number of events within the CNS, including modulating dopaminergic neurotransmission and anxiogenic effects, as well as affecting cognition and nociception. See, e.g., J. N. Crawley and R. L. Corwin, 1994, Peptides, 15:731-755; N. S. Baber, C. T. Dourish, and D. R. Hill, Pain (1989), 39(3), 307-28; and P. De Tullio, J. Delarge and B. Pirotte, Expert Opinion on Investigational Drugs (2000), 9(1), 129-146. Cholecystokinin has been shown to mediate its diverse hormonal and neuromodulatory functions through two receptor subtypes: the CCK-A (CCK-1) and CCK-B (CCK-2) subtypes (see, e.g., G. N. Woodruff and J. Hughes, Annu. Rev. Pharmacol. Toxicol. (1991), 31: 469-501). Both CCK-1 and CCK-2 receptor subtypes belong to the seven transmembrane G-protein-coupled superfamily of receptors. A number of studies suggest that CCK mediates its satiety effect through the CCK-1 receptor, which relays the postprandial satiety signal via the vagal afferents to the CNS. See, e.g., G. P. Smith et al., Science 213 (1981) pp. 1036-1037; and J. N. Crawley et al., J. Pharmacol. Exp. Ther., 257 (1991) pp. 1076-1080. The nucleotide sequences of the peripheral CCK-1 receptor and central CCK-1 receptor are identical in humans. See, e.g., S. A. Wank et al., (1994), NY Acad. Sci. 713, pp. 49-66.
It has been reported that cholecystokinin (CCK) inhibits gastric emptying and increases satiety in a variety of species, including humans, resulting in a reduction of food intake (Moran, T. H. Physiology & Behavior 2004, 82, 175-180). Selective CCK1R antagonists have been shown to reverse the anorexigenic effect of CCK thus increasing food intake and meal size in several species, including humans (Beglinger, C. et. al. Am. J. Physiol. Regul. Integr. Comp. Physiol. 2001, 280, R1149-R1154). Conversely, administration of CCK1R agonists to a variety of species, including humans, results in a reduction of food intake (Geary, N. Physiology & Behavior 2004, 81, 719-733). Consequently, selective small molecule CCK1R agonists are useful for the treatment or prevention of obesity and related metabolic disorders such as diabetes and dyslipidemia (Woods, S. C. Am. J. Gastrointest. Liver Physiol. 2004, 286, G7-13; Moran, T. H., Kinzig, K. P. Am. J. Gastrointest. Liver Physiol. 2004, 286, G183-G188). In humans, bulimia nervosa has been linked with reduced secretion of postprandial CCK (Deylin, M. J. et. al. J. Pharmacol. Exp. Ther. 1987, 241, 100-116), lower CCK concentrations in cerebrospinal fluid (Lydiard, R. B. et. al. Am. J. Psychiatry 1993, 150, 1099-1101), and lower CCK levels in T lymphocytes which could reflect central CCK secretion levels (Brambilla, F. et. al. Psychiatry Research 1995, 37, 51-56). Accordingly, CCK1R agonists are also useful in treating, preventing, or diagnosing bulimia nervosa and related eating disorders.
CCK agonists stimulate gallbladder contraction, stimulate pancreatic enzyme secretions, stimulate intestinal blood flow, and affect intestinal motor activity (See Rehfeld, J. F. Best Practice & Res. Clin. Endocrin. & Metab. 2004, 18, 569-586). Consequently, CCK1R agonists are useful for the treatment, prevention, or diagnosis of disorders related to the gall bladder including, but not limited to, cholecystitis (inflammation of the gallbladder) and cholelithiasis (gallstones). Furthermore, CCK agonists are useful for the treatment, prevention, or diagnosis of disorders related to the pancreas. Finally, CCK1R agonists are useful for the treatment, prevention, or diagnosis of disorders related to the gastrointestinal tract and gastrointestinal motility. CCK receptors are abundant in the central nervous system, and agonists can be used for the treatment, prevention, or diagnosis of emotional or sexual behavior disorders and memory disorders (Itoh, S.; et. al. Drug Develop. Res. 1990, 21, 257-276). Furthermore, CCK agonists can be used for the treatment, prevention, or diagnosis of tardive dyskinesia (Nishikawa, T. et. al. Prog. Neuropsycho-pharmacol. Biol. Psych. 1988, 12, 903-812; Bignon, E. et. al. J. Pharm. Exp. Ther. 1999, 289, 752-761), Parkinson's disease (Bednar, I. et. al. Biogenic Amine, 1996, 12, 275-284), schizophrenia, and psychosis (Crawley, J. N. Trends in Pharmacol. Sci., 1991, 12, 232-236).
Imidazole compounds useful for the treatment of obesity and obesity related disorders have been disclosed in WO 01/085723, WO 03/040107, WO 03/063781, WO 03/007887, WO 2004/094407, WO 2005/009974, WO 2005/040130, WO 2005/063716, WO 2005/095354, US 2005/0054679, US 2005/0124660, US 2005/0197377, U.S. Pat. No. 6,960,601, and J. Med. Chem. 2005, 48, 1823-1838. Other imidazoles are disclosed in J. Med. Chem. 2005, 48, 2638-2645; J. Med. Chem., 2002, 45, 4655-4668; J. Med. Chem. 2000, 43, 3168-3185; and J. Med. Chem. 1997, 40, 1634-1647.
Because of the unresolved deficiencies of the various pharmacological agents discussed above, there is a continuing need for a weight loss treatment with enhanced efficacy and fewer undesirable side effects. The instant invention addresses this problem by providing CCK receptor agonists, and in particular selective agonists of the cholecystokinin-1 receptor (CCK-1R), useful in the treatment and prevention of obesity and obesity-related disorders, including diabetes.
It is therefore an object of the present invention to provide substituted imidazole 4-carboxamides which are selective agonists of the cholecystokinin-1 (CCK-1R) receptor. It is another object of the present invention to provide substituted imidazole 4-carboxamides which are cholecystokinin-1 receptor agonists and thereby useful to treat obesity, diabetes, and obesity related disorders. It is another object of the present invention to provide pharmaceutical compositions comprising the cholecystokinin-1 receptor agonists of the present invention with a pharmaceutically acceptable carrier. It is another object of the present invention to provide methods for the treatment or prevention of disorders, diseases, or conditions responsive to the activation of the cholecystokinin-1 receptor in a mammal in need thereof by administering the compounds and pharmaceutical compositions of the present invention. It is another object of the present invention to provide methods for the treatment or prevention of obesity, diabetes mellitus, and obesity related disorders by administering the compounds and pharmaceutical compositions of the present invention to a mammal in need thereof. These and other objects will become readily apparent from the detailed description that follows.